The invention presented here concerns a wear resistant coating on the working face of disc-shaped machine parts which are made of aluminum of aluminum alloys. In addition, it concerns the use of such coatings on brake discs, in particular those fitted to motorcycles or on clutch plates.
According to the present state of the art, brake discs and clutch plates are manufactured out of steel which is sufficiently wear resistant for the purpose intended. Thus, this material has not needed any kind of special surface treatment. In vehicle manufacture, however, the relatively heavy steel brake discs cause difficulties due to the relatively large unsprung mass which reduces the degree of comfort in driving the vehicle. In the case of clutch plates, the mass should be as little as possible in order to minimize the energy required for its rotation.
For some time now, vehicle and machine manufacturers have wanted to replace the steel by the lighter aluminum. Aluminum, however, has low resistance to frictional wear, and, therefore, the surfaces subjected to frictional contact must be coated with a wear resistant surface. Coating aluminum with steel to improve the wear resistance has in fact been tried, but abandoned again for economic reasons.